This would be an increadible event but the odds are pretty small at this point for an actual collision on Oct 19, 2014. Mars will be about 5.7 arcseconds and set around 9 pm local time on that day. Here is the info...http://spaceobs.org/en/news/

I would hasten to question where the assumption that the comet's nucleus is some 50km in diameter originates.

Currently the IAU Central Bureau for Astronomical Telegrams' ephemeris for the comet is listing an absolute magnitude of +6.0, indicating it to be a very average object. If one takes the nuclear magnitude to be +10.3, it would imply a probable size for the nucleus of more like say 5km, only a tenth of of the size indicated in the article. In contrast, a 50km cometary nucleus is an exceeding rare bird and is what one expects for brilliant comets like Hale-Bopp. As things stand now, C/2013 A1 is certainly no Hale-Bopp!

Wow, this would be exciting to see from earth. The two website above are saying magnitude -4 or -8 as seen from the surface of Mars. Are there an estimates for the apparent magnitude as seen from earth? I know it's probably too early to tell.

Thanks for the heads-up, Darren! I’ve created a diagram with an “overhead” view of C/2013 A1 (Siding Spring), Mars, Earth and Sun. It’s for the months surrounding the comet’s encounter with Mars. It can be seen from the bottom of my comets webpage: www.CurtRenz.com/comets

The only chilling thing to me about this is that it brings *home* the reality these things are still perilous if even remotely. I would have to believe though if this thing hit - Curiosity wouldn't be the close of the current Mars effort and possibly CURIOSITY II would be made and sent to investigate the freshly excavated (if fused and burnt) material from the hit.

It would be tremendous Ill say that. I'd have to believe its extend our Mars program.

I forgot to point out that even though Elenin estimates the comet diameter as 50 km, others (Bortle) recon that absolute brighness equates to a 5 km object. This is fair as a 50 km object is represented by Hale-Bop. Siding Springs doesn't look like its a Hale-Bop class comet.

So thats a 5 km object with a > 600,000 km uncertainty aiming at a 6,800 km cross section ....

Even at 5k that's still huge . The dust kicked up would be off the scale. I'd bet it'd be visible even in an 80mm. What it'd look like though I have no idea. Between the heat from the explosive impact to the sheer force sending dust up into the atmosphere - .

My hunch is its gonna fly right by - but the speculation is entertaining anyway.

If it actually hits the planet, the rovers could likely be toast, and even the orbiters could be destroyed by massive amounts of ejecta.

I bet the ensuing dust cloud would be visible in telescopes. The side of Mars that could be hit is going to face us, correct? I wonder what the time of impact would be and if the we'd be facing Mars at the time to try and watch it live?

That'd be an event to drive a couple hundred miles to get to clear skies for if you can see any kind of flash!!

Mars should be far enough from the sun in October 2014 to be in a dark sky for somebody on this planet to make observations. See Curt's charts further back in this thread. The solar elongation is above 60 degrees I think - could be higher

This would be an increadible event but the odds are pretty small at this point for an actual collision on Oct 19, 2014. Mars will be about 5.7 arcseconds and set around 9 pm local time on that day. Here is the info...http://spaceobs.org/en/news/

I hate to see space media turn into a bunch of divas predicting stuff like this. It degrades them to the level of most television entertainment desperate journalists staving to grab any attention to justify their jobs instead of researching real information, data and facts.